I'm just like you but a little worse. I did fail out of college because of exactly that. I felt such shame at having done D work that I often wouldn't even turn it in, and then get the F.

I struggled for years after dropping out with this, and still do to some extent. But came up with a crazy strategy to kind of get myself addicted to completing tasks on my To Do list. I think today I'm probably significantly more productive than the average person, but I never would have got to this level without going through years of pain and life destroying habits.